Like Feinberg and Sherman (1985) and Phillips and Mason (1992)
we test experimentally whether conglomerate ﬁrms, i.e., ﬁrms competing on multiple structurally unrelated markets, can eﬀectively limit competition. Our more general analysis assumes diﬀerentiated rather than homogeneous products and distinguishes strategic substitutes as well as complements to test this forbearance hypothesis. Rather than only a partners design we also explore a random strangers design to disentangle eﬀects of forbearance and repeated interaction. Surprisingly, conglomerate ﬁrms do not limit competition, they rather foster it. More in line with our expectations we ﬁnd more cooperation in complement markets than in substitute markets and also more cooperation in a partners than in a strangers matching.